The present invention relates to automatic guided vehicles (AGVs) and, more particularly, to an AGV system having interfacing computer sub-systems for controlling guidance, pick-up and delivery, traffic control and internal AGV monitoring.
In the field of material handling, most commonly in a warehouse environment, many articles must be stored in inventory and, an indefinite time later, retrieved for use. The larger the warehouse facility, the greater the number of objects that can be stored.
Moreover, large warehouse facilities require a great amount of geographical space. Not only are modern warehouses spread over a great amount of distance, but their height allows a many objects to be stacked for storage one above the other. Each object location or bin can be identified along three axes: X, Y and Z. Thus, a warehouse location for any specified particular object can be uniquely identified.
When the warehouse is large, it becomes burdensome to move material from one part of it (e.g., the port of entry) to another part thereof (e.g., a storage bin). Moreover, certain warehouses house large objects, weighing many pounds or even tons. The combination of large objects to be stored in a warehouse and great distances between pickup and delivery (P & D) stands is ideal for assigning tasks to automatic guided vehicles. As used herein, the term "assignment" indicates an address of a P & D stand for a pickup operation or for a deliver operation.
It has been found that guided vehicles moving over a buried inductive cable can perform many of the functions that humans perform without the requirement of lighting, heating, ventilation and air conditioning that would normally be required for a pleasant human work environment. Moreover, AGVs can be relied upon to operate continuously 24 hours per day. This advantage of performance over human laborers results in greater efficiency for warehouse facilities.
As AGVs become more sophisticated, they begin to acquire the attributes of intelligent robots. Guiding and maneuvering each AGV and providing the necessary software and control of the AGV requires corresponding sophisticated techniques.
Heretofore, AGV systems have been unreliable. Often these systems caused more problems than they were designed to eliminate. AGV systems have been found to require human intervention, a condition they were to aleviate.
These drawbacks have severely hurt the industry (Ailing robot industry is turning to services, John Holusha, Business Section, New York Times, Page D1, Feb. 14, 1989).
The present invention has combined computerized sub-systems of proven reliability and capability to form an integrated AGV system of advanced design. While it was no simple task to interface all of the various computer sub-systems, once having accomplished this task, the overall AGV system of this invention has shown itself to have versatility and capabilities which are presently unknown in the industry.